Raster image processors are known and used in printers which are capable of printing a line-wise complete page with serially presented data. Typical of these printers is the laser printer in which a light beam is modulated imagewise and deflected line-wise by means of a polygonal mirror onto a light-sensitive surface. The latent image formed on the light-sensitive layer can be developed and transferred to a receiving material such as a sheet of paper.
The graphical data may, for example, be obtained by scanning an image by means of a scanning device and storing the data, with or without the aid of a coding system, in a memory.
The data for a page to be printed is first processed, for example, by means of a graphical work station, to produce a finally desired layout which may contain textual and graphical data.
If an assembled page has to be printed, the graphical information, coded or not coded, and the coded font data are fed to a front-end system along with information relating to height, width and finally desired position. In addition, the bit-map information of the characters to be printed is fed to the front end. This data must then be sent to a printer control. See, for example, U.S. Pat. Nos. 4,031,519; 4,300,206; and European Application No. 0,137,147 A3.
For example, after all the data have been stored in memory in the front end, the raster image processor is adapted to set the data at the correct location in a page size memory (bit-map memory) and to serially read out the page memory to the modulator of a laser printer.
Because modern laser printers are capable of printing pages at high speed and with a high resolution, the raster image processor must be capable of processing the data for said pages at high speed for presentation to the printer. Accordingly, it is an object of the present invention to provide a high speed raster image processor.